Add --format option

[sounisi5011]

Assuming standard GitHub, the format of the version tag is v{version}.
However, some people may want to change this format.
Perhaps it is an edge case, but better than the current situation where there is no choice.

[sounisi5011]

I think we should use the tag-version-prefix option or the version-tag-prefix option instead. These options are used in standard commands.

See: https://github.com/sindresorhus/np/blob/v5.1.0/source/util.js#L51-L65